Abstract <p>Poor germination, vigor and emergence are few major constraints significantly disrupting the yield potential of the onion farming. Being a high value crop, the present study was designed to comprehend the physiological basis of the seed priming induced improvement in onion seeds of variety Punjab Naroya. Laboratory and field studies were carried out in the years 2021 and 2022 amongst seeds primed with various inorganic salts—KNO₃, CaCl₂, KH₂PO₄, K₂HPO₄, Mg(NO₃)₂, ZnSO₄ and plant growth regulators—GA₃ and ethrel in a completely randomized design in Seed Physiology Laboratory, Punjab Agricultural University, Ludhiana, Punjab, India. Priming with 10 ppm ethrel was recorded to be the most effective treatment amongst all for enhancing the germination percentage, seedling vigor and field emergence. Physiological analysis of the priming treatments indicated the major role of the enhanced activities of dehydrogenase and α-amylase enzymes in establishing vigorous seedlings than control. Efficient mobilization of food reserves like starch and utilization of free amino acids for protein reconstitution aided in providing high energy substrates like soluble sugars and proteins for seedling emergence and growth. The current investigation concluded that priming of the onion seeds with 10 ppm ethrel for time duration of 9 h was the most efficient treatment in convalescing low vigor onion seeds of variety Punjab Naroya and improving the germination percentage, early seedling vigor and plant stand under field conditions.</p>